Aerogels with low density and high porosity exhibit outstanding performances as thermal or acoustic insulators. However, most aerogels are mechanically brittle and need further chemical or physical surface treatments to obtain elasticity and superhydrophobicity. Structurally new types of polysilsesquioxane (PSQ) aerogels containing thiourethane as their bridging groups are now reported. These novel PSQ aerogels were prepared from thiourethane bridged silsesquioxane through a simple sol–gel process and vacuum-drying method. The PSQ aerogels exhibit inherent superhydrophobicity, excellent mechanical toughness and good thermal insulation properties. Moreover, the morphology and mechanical performance of these aerogels can be tailored by changing the rigidity of the bridging group.

The stimuli-responsive polypeptides have drawn extensive attention because of their promising applications in biotechnology considering their biocompatibility, biodegradability, and bioactivity. In this tutorial review, we summarize the most recent progress in this area, including thermo-, redox-, photo-, and biomolecule responsive polypeptides over the past decade. The design and synthesis of stimuli-responsive polypeptides will be briefly introduced. The correlation between the structure and properties, particularly the effects of polypeptide conformation, will be emphasized here. In addition, the applications of stimuli-responsive polypeptides in controlled drug release and tissue engineering are briefly discussed.

A series of ABA triblock copolymers of poly(γ-(2-methoxy ethoxy)esteryl-glutamate)-block-poly(ethylene glycol)-block-poly(γ-(2-methoxy ethoxy)esteryl-glutamate) with poly(ethylene glycol) as middle hydrophilic B block and oligo(ethylene glycol)-functionalized polyglutamate (poly-L-EG2Glu) as terminal A blocks were prepared via ring-opening polymerization of EG2Glu N-carboxyanhydride (NCA). The resulting P(EG2Glu)-b-PEG-b-P(EG2Glu) triblocks can spontaneously form hydrogels in water. The intermolecular hydrogen bonding interactions between polypeptides blocks were responsible for the formation of gel network structure. These hydrogels displayed shear-thinning and rapid recovery properties, which endowed them potential application as injectable drug delivery system. The mechanical strength of hydrogels can be modulated by copolymer composition, molecular weight and concentrations. Also, it was found that the hydrogels’ strength decreased with temperature due to dehydration of polypeptide segments. Atomic force microscopy and scanning electron microscopy images revealed that these hydrogels were formed through micelle packing mechanism. Circular dichroism and Fourier transform infrared spectroscopy characterizations suggested the poly-L-EG2Glu block adopted mixed conformation. A preliminary assessment of drug release in vitro demonstrated the hydrogels can offer a sustained release of doxorubicin (DOX) and the release rate could be controlled by varying chemical composition.

A poly(ethylene glycol)-b-poly(L-lysine)-b-poly(styrene) (PEG-PLL-PS) triblock copolymer, which contains a cationic PLL block as the middle block, is synthesized via a combination of ring-opening polymerization (ROP) and atom-transfer radical polymerization (ATRP). The PEG-PLL-PS (ELS) triblock is employed as a macromolecular surfactant to form a stable oil-in-water (O/W) emulsion, which is subsequently used as the template to prepare Janus silica hollow spheres (JHS) via a one-pot biosilicification reaction. For the emulsion template, the middle PLL block assembles at the O/W interface and directs the biomimetic silica synthesis in the presence of phosphate buffer and silicic acid precursors. This biosilicification process takes place only in the intermediate layer between water and the organic interior phase, leading to the formation of silica JHSs with hydrophobic PS chains tethered to the inner surface and PEG attached to the outer surface. The three-layer JHSs, namely, PEG/silica-polylysine/PS composites, were verified by electron microscopy. Upon further breaking these JHSs into species, polymer-grafted Janus silica nanoplates (JPLs) can be obtained. Our studies provide an efficient one-step method for preparing hybrid silica Janus structures within minutes.

Three cysteine derivatives were synthesized in high yield by ligating monomethoxy oligo(ethylene glycol) (OEG) to l-cysteine thiol group using sulfenyl chlorides. These OEG groups containing di-, tri-, and tetra-EG units were linked with l-cysteine via disulfide bond. The three monomers were then converted into corresponding N-carboxyanhydrides (NCAs) using triphosgene in THF. Subsequent ring-opening polymerization (ROP) of disulfide bond containing NCAs gave three poly-EGx-l-cysteine derivatives. The obtained poly-EGx-l-cysteine with x = 3 and 4 displayed thermal-responsive behaviors in water, but the temperature-induced phase transition was found surprisingly irreversible. Such irreversible thermal-responsive behaviors were attributed to cross-linking arising from disulfide bonds exchanges. Using PEG-NH2 as macroinitiator, we also prepared two PEG-b-poly-EGx-l-cysteine diblocks, which could undergo irreversible thermal-induced sol–gel transition, which was caused by the disulfide bonds exchanging reactions. These hydrogels displayed partially shear-thinning and rapid recovery properties allowing new capabilities to construct stimuli-responsive injectable hydrogels in biomedical applications.

The enhanced dispersing capability of these bolaamphiphiles can be attributed to the large aromatic perylene core. The aqueous dispersion efficiency of single-walled carbon nanotubes (SWCNTs) is investigated by UV–vis absorption, fluorescence emission and Raman spectra, scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. It is found that the tetrachloroperylene backbone moieties could interact with SWCNT via synergistic π–π and hydrophobic interactions, and the dispersing properties are closely related to the hydrophilic part of bolaamphiles. This study not only demonstrates tetrachloroperylene derivatives are able to stabilize SWCNTs, but also provides the possibility to understand the structure–property relationship between SWCNTs and tetrachloroperylene-based surfactants.

Laminated nanotapes were fabricated via conformation specific self-assembly of two N-annulated perylene derivatives (NPDs). The assemblies in solvated states were characterized using cryogenic transmission electron microscopy (cryo-TEM), and their nanostructures were modulated by the synergistic interactions of π–π stacking and hydrogen bonds.

Three alkyl-polypeptide (AP) amphiphiles were prepared using ring-opening polymerization of α-amino acid N-carboxyanhydride. The polypeptide segment was composed of diethylene-glycol-monomethyl-ether-functionalized poly-l-glutamate (poly-l-EG2Glu). These AP amphiphiles can spontaneously self-assemble into transparent hydrogels in water. These hydrogels showed shear thinning properties, and their strength can be modulated by hydrophobic alkyl tails. CryoTEM and AFM characterizations suggested that these hydrogels were formed by nanoribbons arising from intermolecular interactions between nonionic poly-l-EG2Glu segments.

The stimuli-responsive polypeptides have drawn extensive attention because of their promising applications in biotechnology considering their biocompatibility, biodegradability, and bioactivity. In this tutorial review, we summarize the most recent progress in this area, including thermo-, redox-, photo-, and biomolecule responsive polypeptides over the past decade. The design and synthesis of stimuli-responsive polypeptides will be briefly introduced. The correlation between the structure and properties, particularly the effects of polypeptide conformation, will be emphasized here. In addition, the applications of stimuli-responsive polypeptides in controlled drug release and tissue engineering are briefly discussed.

Laminated nanotapes were fabricated via conformation specific self-assembly of two N-annulated perylene derivatives (NPDs). The assemblies in solvated states were characterized using cryogenic transmission electron microscopy (cryo-TEM), and their nanostructures were modulated by the synergistic interactions of π–π stacking and hydrogen bonds.

Aerogels with low density and high porosity exhibit outstanding performances as thermal or acoustic insulators. However, most aerogels are mechanically brittle and need further chemical or physical surface treatments to obtain elasticity and superhydrophobicity. Structurally new types of polysilsesquioxane (PSQ) aerogels containing thiourethane as their bridging groups are now reported. These novel PSQ aerogels were prepared from thiourethane bridged silsesquioxane through a simple sol–gel process and vacuum-drying method. The PSQ aerogels exhibit inherent superhydrophobicity, excellent mechanical toughness and good thermal insulation properties. Moreover, the morphology and mechanical performance of these aerogels can be tailored by changing the rigidity of the bridging group.